Which edition (year) of solidworks do you have? It is very likely that the files you are trying to open are of a newer version than the version you are using. I've had the same issue in Inventor before. The easiest solution is to see if you can get them in a step. file format which is very universal to most softwares.
no...it was done by me by the same software which is instaled to my computer. and i used this software to draw the parts. suddenly it was not possible for me to open my file by the same software by which i have drawn my part. .....i want the file with my features is it possible ??????????